The following description relates to elevator brakes and, more particularly, to elevator brakes with elevator brake wedges having low-friction film supporting grooves.
Safety assemblies for certain elevators have a passive part and an active part that moves within the passive part. In some cases, the active part can be provided as wedges that move between non-braking and braking positions relative to a central rail and laterally positioned sliding guides. In order to operate correctly, the wedges need to be self-engaging and capable of disengagement and require a low friction guiding surface to facilitate movement along sliding guide surfaces to guarantee their respective engagement and disengagement with the rail when conditions dictate that the safety assembly be engaged and then disengaged.
Over time, however, it has been seen that the guiding surfaces of the wedges can have reliability and durability issues due to mechanical wear in particular without the introduction of preferential lower friction features to mitigate such conditions. While an industry solution has been to introduce a linear roller bearing assembly between the guiding surfaces of the wedges and sliding guides, the bearings are generally overly thick, complex and expensive. Another alternative has been to use a thin, low friction element (film) that is adhesive bonded to the wedge to provide the necessary low friction guiding surfaces of the wedge adjacent to the sliding guides. Durability of such films remains problematic though because the materials of the low friction guiding surfaces are inherently difficult to bond to the wedges or retain their bond strength during usage of the safety assemblies.